Structure of eukaryotic cells

Question 1

Describe the Structure and function of the cell-surface membrane

Answer 1

Structure:
-phospholipid bilayer with embedded proteins
-Selectively permeable so enables control of passage of substances in and out of cells

Function:
-Barrier between internal and external environment

Question 2

Describe the Structure and function of the nucleus

Answer 2

-Nuclear envelope, nuclear pores, nucleolus , DNA
-controls the cells activity through transcription on mRNA
-Nuclear pores allows substances e.g. mRNA to move between the nucleus and cytoplasm
-Nucleolus makes ribosomes which are made up of proteins and ribosomal RNA

Question 3

Describe the Structure and function of the mitochondria

Answer 3

Structure:
Double membrane – inner membrane folded to form cristae.

Matrix containing small 70S ribosomes, small circular DNA and enzymes
involved in aerobic respiration (glycolysis).

Function
- Site of aerobic respiration producing ATP for energy release

Question 4

Describe the Structure and function of the Golgi apparatus

Answer 4

Structure
3 or more fluid filled membrane bound sacs with vesicles at edge

Function:
Receives protein from rough endoplasmic reticulum

Modifies/processes protein

Packages into vesicles e.g. for transport to cell surface membrane for exocytosis

Also makes lysosomes

Question 5

Describe the structure and function of lysosomes

Answer 5

Structure:
Type of Golgi Vesicle containing lysozymes (hydrolytic enzymes)

Function:
Release of lysozymes to hydrolyse pathogens

Question 6

Describe the Structure and function of ribosomes

Answer 6

Structure
Float free in cytoplasm or bound to rER. Made from 1 large and 1 small subunit.

Function
- Site of protein synthesis, specifically, translation.

Question 7

Describe the Structure and function of the rough endoplasmic reticulum

Answer 7

Ribosomes bound by a system of membranes

Folds polypeptides to secondary / tertiary structure

Packages to vesicles, transport to the Golgi apparatus etc.

Question 8

Describe the Structure and function of the smooth endoplasmic
reticulum

Answer 8

System of membranes

function:
synthesises and processes lipids

Question 9

Describe the Structure and function of chloroplasts (plants and algae)

Answer 9

Structure:
Thylakoid membranes are stacked up in some parts to form grana, which are linked by lamellae. These sit in the stroma and are surrounded by a double membrane. Also contains starch granules and circular DNA.

Function:
(Chlorophyll) absorbs light for photosynthesis to produce organic substances

Question 10

Describe the Structure and function of the cell vacuole (plants)

Answer 10

Structure
Contains cell sap – a weak solution of sugars and salts. Surrounding membrane is
called the tonoplast.

Function
Maintains pressure in the cell (stop wilting)
Stores/isolates unwanted chemicals in the cell

Question 11

Describe how specialised cells are organised in complex multicellular organisms

Answer 11

Specialised cell – the most basic functional subunit in all living organisms, specialised for a particular function

Tissue – Group of organised specialised cells; joined and working together to perform a particular function; often with the same origin

Organ – Group of organised different tissues; joined and working together to perform a particular function

Organ system – Group of organised organs; working together to perform a particular function

Question 12

Explain how epithelial cells in the small intestine are specialised for efficient absorption.

Answer 12

Villi and microvilli increase surface area.

Lots of mitochondria to provide energy e.g. for active transport